7-Eleven marks birthday by giving away free Slurpees

7-Eleven is marking its 86th birthday with its annual free Slurpee day!

As part of Thursday's promotion, participating stores in the U.S. and Canada are giving away 12-ounce Slurpees from 11 a.m. to 7 p.m.

According to the company's website, customers consume nearly 13 million Slurpee drinks each month. Company officials say the beverage was introduced in 1966, and almost 6.5 billion Slurpees have been sold since then.

7-Eleven says it's the world's first convenience store. It was born in the summer of 1927 in suburban Dallas. It now has more than 50,000 stores in 16 countries. About 10,000 of those are in North America.